High-pressure discharge lamps may use a discharge vessel which has two oppositely directed connecting elements in the form of shafts. The bulb is made of a suitable transparent material, typically glass, the current supply elements being connected trough the bulb material by being melted therein, for example through presses or pinch connections. One of the shafts can be directly connected to a base made of a heat-resistant, electrically insulated material, for example a ceramic. The base has two terminal elements, one of which is connected to a shaft, and the other to an electrical conductor which leads to the shaft remote from the one connected in the base.
The lamp to which the present invention relates is known, for example shown in the referenced U.S. Pat. No. 4,533,851, to which German Patent Disclosure Document DE-OS 32 36 462 corresponds. If such lamps have been operated, and are to be re-started, that is, are to be re-started under hot conditions, and require instantaneous re-starting, a starting voltage of more than 20 kV may be required to insure reliable re-starting and operating reliability with respect to the electrical data of the lamp. Due to the construction of the lamp, the base body is subjected to high thermal loading. The heat of the base body is transferred to the lamp unit, and may be transferred to a socket; the heating reduces the lifetime of the lamp and, after disconnection of electrical current, may delay cooling of the lamp unit itself. Current supply to one of the terminal elements previously was through an angled terminal element which leads to a comparatively long spacing between terminals, and hence an overdimensioned base structure. The size of the base structure then results in high heat capacity thereof, which is undesirable. If the lamp is to be introduced into a reflector, the apex of the reflector must be formed with an aperture large enough to receive the base, and an increase in the size of the base requires an increase in the cut-out of the reflector, thus reducing the light available from the lamp since less of the light can be reflected. An engagement surface of the base with an appropriate prior-art socket was formed by a collar at the lower side of the base, and surrounding the contacting terminal elements. The distance from the socket through the base to the lamp, thus, was increased, thereby reducing the accuracy with which the lamp itself can be positioned in a reflector, for example.